Lagoon Brittle Star

Ophiocoma scolopendrina, as other brittle stars, have long, thin arms emanating from a small, disk-shaped body and are about the size of an outstretched human hand. They belong to the phylum of echinoderms, which includes sea urchins, sea cucumbers, and sea stars. Dorsal disc and dorsal arm plates vary from variegated black to pale brown. They are irregularly banded. O. scolopendrina can reach a length of about 13cm, while the disc diameter can reach up to 25mm. The star's sexes can be identified by checking slits between the arms, which expose the white male spermaries and red female ovaries.

Ophiocoma scolopendrina can be found in the Red Sea, the tropical Indo-Pacific region, Taiwan, Eastern Africa, Southeastern Polynesia, the Marshall Islands, and Madagascar. Their typical density is about 20 individuals per 1 m2.

These brittle stars are present in crevices and under boulders of intertidal reef platforms in the upper and middle eulittoral. They have also been seen underneath coral rubble. They typically hide amongst concealing vegetation during surface-film feeding. They live primarily in areas with shallow water strictly in the intertidal and are often observed sweeping their arms over sand or coral substrata.

When feeding, O. scolopendrina changes its location depending on tide positionality. Stars have been observed to be nearly entirely concealed at high tide, and expose themselves progressively as the tide becomes lower. Unlike other brittle star species, these stars have evolved an adaptation that lets them participate in surface-film feeding during both low and flooding tides. This adaptation allows them to consume neuston and detrital particles and film that are found suspended on the surface of sea water.

Ovarian substances have been noted to induce male spawn. Adult female stars each contain an estimated 12 * 10⁵ premature oocytes and it is believed that all adult O. scolopendrina produce gametes throughout the remainder of their lives. They consistently produce gametes at all studied ages. O. scolopendrina reproduce continuously throughout the year, as once gametes are available in the gonads, allowing them to spawn regardless of season. Ophiocoma scolopendrina have planktonic planktotrophic larvae and have been observed to spawn in large numbers.